Give away free New Testaments or simply a free Gospel of St. John to anyone who wants one. When people who are curious start reading, they just might get interested in learning more. (I mean, don’t embarrass them by handing out New Testaments, but maybe have a stack of them free for the taking near the front door of the church).
Give them links to online Bibles they can read, and good Catholic Bible teachers, so they can listen to podcasts or streaming audio. Maybe add a webpage or RSS feed to a parish’s existing website with links to recommended online resources.
Give them a way to get their questions answered, like maybe a weekly, biweekly or monthly Bible discussion at a local coffee shop. (A church in my community does this and calls it Brew Theology.)
Give them local parish discussion content on Facebook, Twitter, Instagram, et. al. Enlist well grounded Catholics of your parish to post content and respond to replies, especially young Catholics, as teens are looking for causes to work for together.
Give them the links to forums like this and tell them to say hi when they stop by!